Abstract
An electrochemical cell comprising a novel dual‐component graphite and Earth‐crust abundant metal anode, a hydrogen producing cathode and an aqueous sodium chloride electrolyte was constructed and used for carbon dioxide mineralisation. Under an atmosphere of 5 % carbon dioxide in nitrogen, the cell exhibited both capacitive and oxidative electrochemistry at the anode. The graphite acted as a supercapacitive reagent concentrator, pumping carbon dioxide into aqueous solution as hydrogen carbonate. Simultaneous oxidation of the anodic metal generated cations, which reacted with the hydrogen carbonate to give mineralised carbon dioxide. Whilst conventional electrochemical carbon dioxide reduction requires hydrogen, this cell generates hydrogen at the cathode. Carbon capture can be achieved in a highly sustainable manner using scrap metal within the anode, seawater as the electrolyte, an industrially relevant gas stream and a solar panel as an effective zero‐carbon energy source.
Highlights
The only carbon capture technology that has been implemented on a large scale is amine-based carbon dioxide capture,[1,2] which consumes 0.2–0.5 megawatt-hours per metric tonne of carbon dioxide (MWh tCO2 À1) removed and pressurized to 150 bar.[3]
To demonstrate that the cell would capture carbon dioxide, 1 m aqueous sodium chloride was used as electrolyte and a gas stream comprising 5 % carbon dioxide and 95 % nitrogen was passed across the surface of the electrolyte at a flow rate of 14 mL minÀ1, whilst the solution was agitated by a stirrer bar
During the first 7 h, the cell was at open circuit and the carbon dioxide level in solution reached equilibrium with the gas-phase carbon dioxide level, as indicated by both the gas trace and the stabilisation of the pH
Summary
The only carbon capture technology that has been implemented on a large scale is amine-based carbon dioxide capture,[1,2] which consumes 0.2–0.5 megawatt-hours per metric tonne of carbon dioxide (MWh tCO2 À1) removed and pressurized to 150 bar.[3]. Ty from low carbon, sustainable power sources such as solar, tidal or wind energy. Such technology could be applied to capturing carbon dioxide from chemical sources. Despite the appeal of trapping carbon dioxide in the form of an inert solid, previous electrochemical mineralisation technologies have been limited by their requirement for expensive ion-selective membranes that ensure that the concentration of carbonate is high enough to sustain rapid precipitate formation.[20,21,22] it has been shown that carbon electrodes can be used to reversibly uptake carbon dioxide from the gas phase into aqueous sodium chloride solution through supercapacitive swing adsorption.[23,24] This suggests that this technology could be adapted as a “reagent concentrator” component within an unprecedented dual-material anode capable of performing irreversible carbon mineralisation through the combination of both electrocapacitive carbon capture and sacrificial metal oxidation.
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